Solid-State Refrigeration Based on the Electrocaloric Effect for Electronics Cooling

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Y. Sungtaek Ju
Keyword(s):  
Solid State ◽  
Experimental Studies ◽  
Heat Diffusion ◽  
Coefficient Of Performance ◽  
Irreversible Processes ◽  
Design Parameters ◽  
Cooling Power ◽  
Electrode Arrays ◽  
Actual Performance ◽  
The Impact

Subambient temperature operations of advanced semiconductor devices offer many benefits, including improved reliability, reduced leakage currents, and enhanced signal to noise ratios. We discuss a new design concept for compact solid-state refrigerators based on the electrocaloric (EC) effect. The EC refrigerators are attractive because they may approach the Carnot efficiency more closely than Peltier coolers, which involve intrinsically irreversible processes. To address parasitic losses and other practical considerations that limit the actual performance of EC coolers, we incorporate laterally interdigitated electrode arrays with high effective thermal conductivity and switchable thermal interfaces with high switching ratios and high off-state thermal resistance. Numerical simulations are used to quantify the impact of various design parameters and the expected performance of the module, focusing in particular on the heat diffusion time and RC thermal time constant. Based on the material properties reported in the literature, we project that cooling power densities >10 W/cm2 may be achieved across ΔT of the order of 10 K at coefficient of performance (COP)>10. The present work motivates further experimental studies to develop advanced electrocaloric materials and fabricate/test cooling modules to assess the feasibility of their practical application.

scholarly journals A novel model and design of a MEMS Stirling cooler for local refrigeration

2021 ◽  
Vol 313 ◽  
pp. 10001
Author(s):  
Sylvie Bégot ◽  
Muluken GETIE ◽  
Alpha Diallo ◽  
François Lanzetta ◽  
Magali Barthès ◽  
...  
Keyword(s):  
Microelectromechanical Systems ◽  
Coefficient Of Performance ◽  
Squeeze Film ◽  
Design Parameters ◽  
Cooling Power ◽  
Macro Scale ◽  
Stirling Engines ◽  
Parametric Studies ◽  
Scale Design ◽  
The Impact

In this paper, we present a new model design and parametric studies of a miniature Stirling cooler machine for on-site refrigeration. The MEMS (Microelectromechanical systems) technology is investigated to design this machine. The concept could be used to provide cooling at chip scale and mitigate hot spots in electronic devices. Whereas numerous works deal with Stirling engines at a macroscopic scale, only a few works concern miniaturized Stirling engines. Therefore, a model analysis giving insights of the impact of the technological choices and downsizing of the machine is needed. A base design model is presented. The model results lead to a cooling power of 10 mW and a Coefficient Of Performance of 1.45. A parametric study is conducted for operational and design parameters. Compared to macro-scale design, the same trend is observed for the influence of the thermal performance regenerator. Different trends from macroscopic engines were observed for hysteresis losses importance, and the choice of the working gas. The raise in power due to the raise in frequency expected for micro-scale devices is counterbalanced by the degradation of the COP due to the increase in thermofluidic losses. Squeeze film damping and finite speed losses can be neglected at this scale.

Analytical and Experimental Studies on Induced Current Switching by a Fault-Proof Gas Insulated Earthing Switch

2010 ◽  
Vol 11 (5) ◽  
Author(s):  
Mandava Mohana Rao ◽  
Moutusi Paul ◽  
H.S. Jain
Keyword(s):  
Short Circuit ◽  
Experimental Studies ◽  
Short Circuit Current ◽  
Design Parameters ◽  
Induced Current ◽  
Current Switching ◽  
Test Circuit ◽  
Reliable Performance ◽  
Gas Insulated Substation ◽  
The Impact

Fault-proof earthing switches are one of the important modules of a gas insulated substation, as it enables make at 100 percent short circuit current, which is functionally different from maintenance earthing switches. The fault-proof earthing switch shall be designed to make and break electro-magnetically and electro-statically induced currents as per IEC-62271-102. The paper discusses the impact of “test circuit configurations and voltage” on test parameters for gas insulated fault-proof earthing switch utilizing simulation with PSCAD software. Authors record the development of a 145 kV gas insulated fault proof earthing switch by considering novel design features like minimum arcing/pre-arcing time, effective current transfer from arcing contact to ground terminal, etc. The development has been evaluated successfully for electro-magnetically and electro-statically induced current duties as per IEC. Finally, design parameters to be considered for ensuring reliable performance during induced current switching from fault-proof earthing switches are also discussed.

scholarly journals Numerical and Experimental Investigations on Optimized 3D Compressor Airfoils

2018 ◽  
Author(s):  
Jan Mihalyovics ◽  
Christian Brück ◽  
Dieter Peitsch ◽  
Ilias Vasilopoulos ◽  
Marcus Meyer
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Experimental Studies ◽  
Total Pressure Loss ◽  
Design Parameters ◽  
Flow Conditions ◽  
Flow Angle ◽  
Flow Phenomena ◽  
The Impact ◽  
Stator Design

The objective of the presented work is to perform numerical and experimental studies on compressor stators. This paper presents the modification of a baseline stator design using numerical optimization resulting in a new 3D stator. The Rolls Royce in-house compressible flow solver HYDRA was employed to predict the 3D flow, solving the steady RANS equations with the Spalart-Allmaras turbulence model, and its corresponding discrete adjoint solver. The performance gradients with respect to the input design parameters were used to optimize the stator blade with respect to the total pressure loss over a prescribed incidence range, while additionally minimizing the flow deviation from the axial direction at the stator exit. Non-uniform profile boundary conditions, being derived from the experimental measurements, have been defined at the inlet of the CFD domain. The presented results show a remarkable decrease in the axial exit flow angle deviation and a minor decrease in the total pressure loss. Experiments were conducted on two compressor blade sets investigating the three-dimensional flow in an annular compressor stator cascade. Comparing the baseline flow of the 42° turning stator shows that the optimized stator design minimizes the secondary flow phenomena. The experimental investigation discusses the impact of steady flow conditions on each stator design while focusing on the comparison of the 3D optimized design to the baseline case. The flow conditions were investigated using five-hole probe pressure measurements in the wake of the blades. Furthermore, oil-flow visualization was applied to characterize flow phenomena. These experimental results are compared with the CFD calculations.

From Chip to Cooling Tower Data Center Modeling: Influence of Chip Temperature Control Philosophy

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Ed J. Walsh ◽  
Thomas J. Breen ◽  
Jeff Punch ◽  
Amip J. Shah ◽  
Cullen E. Bash
Keyword(s):  
Heat Sink ◽  
Data Center ◽  
Energy Performance ◽  
Coefficient Of Performance ◽  
Control Algorithms ◽  
Cooling Power ◽  
Operational Strategies ◽  
The Impact ◽  
Heat Sink Temperature

The chiller cooled data center environment consists of many interlinked elements that are usually treated as individual components. This chain of components and their influences on each other must be considered in determining the benefits of any data center design and operational strategies seeking to improve efficiency, such as temperature controlled fan algorithms. Using the models previously developed by the authors, this paper extends the analysis to include the electronics within the rack through considering the processor heat sink temperature. This has allowed determination of the influence of various cooling strategies on the data center coefficient of performance. The strategy of increasing inlet aisle temperature is examined in some detail and found not to be a robust methodology for improving the overall energy performance of the data center, while tight temperature controls at the chip level consistently provide better performance, yielding more computing per watt of cooling power. These findings are of strong practical relevance for the design of fan control algorithms at the rack level and general operational strategies in data centers. Finally, the impact of heat sink thermal resistance is considered, and the potential data center efficiency gains from improved heat sink designs are discussed.

Theoretical and experimental studies for wind turbine’s shrink disk

2014 ◽  
Vol 229 (2) ◽  
pp. 325-334 ◽  
Author(s):  
Wang Jianmei ◽  
Kang Jianfeng ◽  
Tang Liang
Keyword(s):  
Contact Pressure ◽  
Experimental Studies ◽  
Frictional Coefficient ◽  
Thick Wall ◽  
Design Parameters ◽  
Design Calculation ◽  
Interference Fit ◽  
Mating Surface ◽  
Actual Operation ◽  
The Impact

With the wide application of multi-layer interference fit in many engineering fields, as for key component in the wind turbine generator, wind turbine’s shrink disk uses interference fit to transmit rated torque and axial force. In order to ensure the work reliability of shrink disk during the actual operation, the paper presents a more precise method on the design calculation of contact pressure on the mating surfaces with interference fit. In accordance with the order from the inside to the outside, the contact pressure of spindle-to-sleeve surface can be calculated based on the rated load required to transmit. Combining with Thick-wall Cylinder Theory and Lame Equation, taking into account the impact of fit clearance, the checking method of the bushing was used to calculate the contact pressure on mating surface of bushing-to-inner ring; and the stress analysis of the inner ring was used to calculate the contact pressure on mating surface of inner ring-to-outer ring. At the same time, the effects of frictional coefficient, fit clearance, and other design parameters on theoretical results were also analyzed. The pressure distribution of each mating surface was obtained by Abaqus software simulation, which showed that the results from improved method was closer to simulation results and had higher accuracy than traditional method by comparing the results with three different methods. Finally, the test was designed to verify whether the shrink disk could bear the load or not on the test platform of shrink disk, and the results indicated that it could meet the requirements of given loadcase.

EXPERIMENTAL INVESTIGATION OF A REFRIGERATION SYSTEM WORKING UNDER TRANSIENT CONDITIONS

2014 ◽  
Vol 22 (03) ◽  
pp. 1450013 ◽  
Author(s):  
J. K. DABAS ◽  
SUDHIR KUMAR ◽  
A. K. DODEJA ◽  
K. S. KASANA
Keyword(s):  
Capillary Tube ◽  
Coefficient Of Performance ◽  
Tube Length ◽  
Design Parameters ◽  
Transient Operation ◽  
Refrigeration System ◽  
Transient Conditions ◽  
Cooling Period ◽  
Optimum Selection ◽  
The Impact

The impact of transient conditions along with varied capillary tube length and charge quantity over the performance of a simple refrigeration system under all time transient operations has been investigated in a specially designed experimental setup. A maximum drop of 75% in the coefficient of performance (COP) of the system was recorded by the end of the transient cooling period. The continuous deterioration in performance from start to end of the transient cooling job can be well minimized by the optimum selection of capillary tube length and charge quantity. This paper refers some of the existing methods to determine the appropriate length of the coiled capillary tube and charge quantity for a newly designed refrigeration machine working under steady state conditions and compares the experimental results of transient operation with these. Optimum charge quantity for transient operation in the present study is 3.5% to 5% less than that calculated by the existing analytical and numerical methods. The optimum length of coiled capillary tube for transient operation as found in this experimental study matches approximately with the length predicted by the existing dimensionless correlation on the basis of design parameters as estimated towards the end of the transient cooling period.

scholarly journals Analysis of the influence of design parameters on the agro-ecological qualities of tractor tires

2021 ◽  
Vol 937 (3) ◽  
pp. 032010
Author(s):  
V Kravchenko ◽  
L Kravchenko ◽  
V Oberemok ◽  
A Avanesyan
Keyword(s):  
Experimental Studies ◽  
Simulation Models ◽  
Contact Spot ◽  
Design Parameters ◽  
Physical Processes ◽  
Software Environment ◽  
Ground System ◽  
Mobile Machinery ◽  
The Impact ◽  
Normal Deflection

Abstract Experimental studies of the impact of agricultural mobile machinery movers on the soil are seasonal in nature and require complex experimental equipment. The complexity of the physical processes occurring in the elastic wheel-ground system requires the introduction of many assumptions and limitations that reduce the accuracy of the results, according to the design of simulation models performed in the software environment. The aim of the research was to study the influence of the design parameters of the tire on the efficiency of the normal deflection along the contact spot zone X. Studies have shown that 65% to 77% of the normal deflection of the tire is used when passing the contact spot. The reinforcement parameters of the tire frame have the greatest impact on the efficiency of the normal deflection along the contact spot zone. With an increase in the number of layers of the frame cord from 2 to 8, the coefficient of usability of the normal deviation for the stroke of the contact spot decreases from 0.761 to 0.689, with an increase in the angle of inclination of the frame cords - decreases from 0.755 to 0.693.

Aircraft wing design at low speeds using Taguchi method

2018 ◽  
Vol 90 (1) ◽  
pp. 51-55
Author(s):  
Mustafa Soylak ◽  
Nurseda Karagöz Gökçe ◽  
Eyüp Sabri Topal
Keyword(s):  
Reynolds Number ◽  
Taguchi Method ◽  
Experimental Studies ◽  
Design Stage ◽  
Design Parameters ◽  
Wing Design ◽  
Aircraft Wing ◽  
Content Type ◽  
Low Speeds ◽  
The Impact

Purpose The purpose of this paper is to determine the impact level of parameters affecting wing design at low speeds using Taguchi method. Design/methodology/approach Using brain storming approach airfoil shape, wing angle of attack and Reynolds number are determined as important wing design parameters. Most important parameters over these parameters are determined using Taguchi method. The lift-to-drag ratio (CL/CD ratio) is chosen as the performance criterion and L8 orthogonal index is chosen as experimental study scheme for this study. Findings Experimental results are examined using Taguchi method. After making experiments and also analyses, Reynolds number is found as the most important and identifier parameter for aircraft wing design. Practical implications Taguchi method makes the experimental design for experimental studies. This method reduces the number of experiments substantially using orthogonal indices while keeping effects of uncontrolled parameters to a minimum. Reduction in number of experiments helps save time and also cost. Originality/value In this study, with less number of experiments, the most important parameter for aircraft wing design is determined. Moreover, with less number of experiments, not only is time saved but the design stage is also made faster.

scholarly journals Variable-Load Heat Pumps: Impact of the Design and Control Parameters on the Actual Operation Conditions

2021 ◽  
Vol 65 (2-4) ◽  
pp. 371-377
Author(s):  
Alice Mugnini ◽  
Gianluca Coccia ◽  
Fabio Polonara ◽  
Alessia Arteconi
Keyword(s):  
Control Strategies ◽  
Residential Building ◽  
Energy Performance ◽  
Heat Pumps ◽  
Design Parameters ◽  
Variable Load ◽  
Actual Performance ◽  
Operation Conditions ◽  
And Control ◽  
The Impact

Nowadays heat pumps (HPs) represent the main alternative to traditional heating systems for the transition to nearly zero-energy buildings. Though HPs are a well-known technology, the estimation of their actual energy performance is still under discussion. Indeed, the proper choice of the HP design parameters (e.g. size, rated supply temperature) and the adopted control strategy can assume a paramount role to cover the mismatch between declared and actual performance of the system. Objective of this work is to analyze this mutual dependence in an operating system to provide guidelines for the design of a residential heating system with a HP. Through a dynamic energy simulation tool, a variable-load air-to-water HP is used to cover the thermal demand of a residential building. The effect of the reciprocal influence of different design choices (e.g. rated heating capacity or design supply temperature) and control strategies (e.g. climatic regulation) is analyzed by simulating different scenarios. To complete the evaluation, the impact of a thermal energy storage is also assessed. The study allows to identify guidelines for the design of different system configurations and results seem to confirm the impact of the investigated parameters on the seasonal performance of the system.

scholarly journals Numerical and Experimental Studies of the ŁK Type Shaped Charge

2020 ◽  
Vol 10 (19) ◽  
pp. 6742 ◽  
Author(s):  
Dariusz Pyka ◽  
Adam Kurzawa ◽  
Miroslaw Bocian ◽  
Marcin Bajkowski ◽  
Mariusz Magier ◽  
...  
Keyword(s):  
Experimental Studies ◽  
Design Parameters ◽  
Simulation Studies ◽  
Initiation System ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Smoothed Particle Hydrodynamics Method ◽  
The Impact ◽  
Positive Effect ◽  
Explosive Detonation

In this paper, the authors presented an analysis of the strengthening of the cumulative jet by the appropriate formation of the detonation wave front acting under the influence of high pressure on the liner. The analysis of the Polish ŁK cumulative charge was carried out using numerical methods in the ABAQUS program. Simulation studies were carried out on axial and peripheral initiations of the explosive cumulative liner. For this purpose, two types of cumulative charges were made with the same design parameters, differing only in the explosive detonation-initiation system. The impact of the elastomer insert on the focusing of the cumulative jet was verified. The influence of peripheral and axial initiation on a cumulative jet’s velocity was investigated. The authors proposed a new conical insert placed in the explosive between the pocket for the detonator and the liner, also changing the material of the cumulative liner. The smoothed-particle hydrodynamics method was used to describe the formation of a cumulative jet. The obtained results were verified experimentally, and they show that modification of the ŁK charge has a positive effect on jet amplification, with an inevitable collapse in the final stage of formation. The obtained results correlate with the literature’s data.

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